METHOD OF INHIBITING COMPLEMENT ACTIVATION WITH FACTOR Bb SPECIFIC ANTIBODIES

ABSTRACT

A process of inhibiting the adverse effects of alternative complement pathway activation products in a subject includes administering to the subject an amount of anti-factor Bb antibody effective to selectively inhibit formation of an alternative complement pathway activation products C3a, C5a, and C5b-9, and activation of neutrophils, monocytes, and platelets.

RELATED APPLICATION

This application claims priority from U.S. Provisional Application No.60/968,146, filed Aug. 27, 2007, the subject matter, which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to complement activation. Particularly,the present invention relates to a method for inhibiting complementactivation via the alternative pathway.

BACKGROUND OF THE INVENTION

The complement system is responsible for initiating and amplifying theinflammatory response to microbial infection and other acute insults.Inappropriate activation of complement has been implicated inpathological situations. For instance, the complement system has beenimplicated in contributing to the pathogenesis of several acute andchronic conditions, including atherosclerosis, ischemia-reperfusionfollowing acute myocardial infarction, Henoch-Schonlein purpuranephritis, immune complex vasculitis, rheumatoid arthritis, arteritis,aneurysm, stroke, cardiomyopathy, hemorrhagic shock, crush injury,multiple organ failure, hypovolemic shock and intestinal ischemia,transplant rejection, cardiac Surgery, PTCA, spontaneous abortion,neuronal injury, spinal cord injury, myasthenia gravis, Huntington'sdisease, amyotrophic lateral sclerosis, multiple sclerosis, GuillainBarre syndrome, Parkinson's disease, Alzheimer's disease, acuterespiratory distress syndrome, asthma, chronic obstructive pulmonarydisease, transfusion-related acute lung injury, acute lung injury,Goodpasture's disease, myocardial infarction, post-cardiopulmonarybypass inflammation, cardiopulmonary bypass, septic shock, transplantrejection, xeno transplantation, burn injury, systemic lupuserythematosus, membranous nephritis, Berger's disease, psoriasis,pemphigoid, dermatomyositis, anti-phospholipid syndrome, inflammatorybowel disease, hemodialysis, leukopheresis, plasmapheresis,heparin-induced extracorporeal membrane oxygenation LDL precipitation,extracorporeal membrane oxygenation, and macular degeneration.

Complement can be activated through three distinct enzymatic cascades,referred to as the “classical”, “Lectin/MBL”, and “alternative” pathways(CP, MBL, and AP respectively). These pathways are shown schematicallyin FIG. 1. The AP is responsible for 80-95% of total complementactivity. Both classical and alternative pathways have the ability toproduce C3a and C5a. However, the level of these anaphylatoxins variesdepending upon which pathway is active. Lectin pathway is a variation ofthe classical pathway. Alternative pathway is activated in a number ofdisease indications. There are three specific proteins Factors B, D, andP that play a major role in the initiation and propagation of the AP.The terminal complex is known as MAC which is responsible for lysis.Both C3a and C5a are potent anaphylatoxins that are responsible foractivating platelets, neutrophils, and monocytes and inflammatorymolecules, such as elastase, TNF, IL-1, VEGF, and peroxides arereleased.

Factor B is composed of two discrete domains Ba (molecular weight, 33kDa) and Bb (molecular weight, 60 kDa). The Ba domain consists of threeshort consensus repeats known as SCR1, SCR2, and SCR3 (FIG. 3). It hasbeen shown using mutation analysis and with the use of specific Bamonoclonal antibodies that the factor B functional domain is located inthe SCR3 region. The SCR region was used to produce antibodies thatdemonstrated clinical benefit in several animal models of diseases. TheBb domain of factor B contains the Von Willowbrand (VWF) domain inaddition to the serine protease domain. Various studies have shown thatit is the Ba domain that is important for factor B function, and thatinhibition of factor B binding to C3b was required for inhibition ofcomplement activity.

Properdin, a small but important molecule binds C3b to form P-C3bcomplex. Factor B binds both free C3b and P-C3 to form C3bB and PC3bBcomplexes. These complexes are cleaved by factor D to form, C3bBb andPC3bBb, both of which possess C3-convertase activity. The resultingconvertase can cleave C3, into C3b and C3a. The newly produced C3bfragment, which covalently attaches to the target and then interactswith factors B and D to form the additional alternative pathway C3convertase molecules.

Referring to FIG. 2, which is a schematic illustration of AP activation,it is known that the alternative pathway C3-convertase is stabilized byC3b-bound properdin. Since the substrate for the alternative pathwayC3-convertase is C3, C3 is therefore both a component and a product ofthe reaction. As the C3-convertase generates increasing amounts of C3b,an amplification loop is established. Furthermore, the classical pathwaycan also generate C3b which can bind factor B and thereby engage thealternative pathway even though the trigger is CP mediated. This allowsmore C3b to deposit on a target leading to enhanced amplification of APactivation. All three, the classical, the lectin, and the alternativepathways converge at C3, which is cleaved by the C3 convertase to formC3b and C3a. C3a is a potent anaphylatoxin and has been implicated inthe pathogenesis of a variety of clinical indications. C3a activatesneutrophils, monocytes, platelets, mastcells, and T lymphocytes. C3a hasbeen shown to be important for the induction of paw edema in anadjuvant-induced arthritis model.

Addition of newly formed C3b to the existing C3 convertase forms C5convertase, which cleaves C5 to produce C5b and C5a. C5a similar to C3ais also a potent anaphylatoxin that causes alterations in smooth muscle,in vascular tone, and in vascular permeability. It is also a powerfulchemotaxin and an activator of neutrophils, monocytes, platelets,endothelial cells, and T lymphocytes. C5a-mediated cellular activationcan significantly amplify inflammatory responses by inducing the releaseof additional inflammatory mediators, including cytokines, hydrolyticenzymes, arachadonic acid metabolites and reactive oxygen species.

The cleavage of C5 produces C5b and C5a. Anaphylatoxin C5a is releasedand C5b inserts itself into the lipid bilayer and acts as a nucleus forC6, C7, C8, and C9 deposition to form the C5b-9 complex at the surfaceof the target cell. C5b-9 is also known as the membrane attack complex(MAC). There is now strong evidence that MAC may play an important rolein inflammation in addition to its role as a lytic pore-forming complex.In addition to the proven role of C3a, C5a in platelet activation, C5b-9is also known to mediate activation of platelets. Thus, there issignificant evidence suggesting C3a, C5a, and MAC involvement inactivation of platelets. Regardless of the method of plateletactivation, activated platelets express CD62P also called P-selectin.P-selectin also mediates platelet-monocyte conjugation, and such bindingtriggers the release of tissue factor from monocytes. One result of suchconjugate formation is the removal of platelets from the circulation, aphenomenon that can contribute to the development of thrombocytopenia.

While complement activation provides a valuable first-line defenseagainst potential pathogens, the activities of complement that promote aprotective inflammatory response can also represent a potential threatto the host. For example, C3a and C5a anaphylatoxins recruit andactivate neutrophils, monocytes and platelets to the pathological site.These activated cells are indiscriminate in their release of destructiveenzymes and may cause organ damage. Currently, no approved drugs existthat can inhibit the damages caused by the inappropriate activation ofthe complement pathway. Based upon the available clinical data, itappears that in most acute injury settings, complement activation ismediated predominantly via the alternative pathway. Therefore,developing suitable methods that inhibit only this pathway withoutcompletely obviating the immune defense capabilities would be highlydesirable. This would leave the classical pathway intact to handleimmune complex processing and to aid in host defense against infection.

SUMMARY OF THE INVENTION

The present invention relates to a process of inhibiting the adverseeffects of alternative complement pathway activation products in asubject. The process includes administering to the subject an amount ofanti-factor Bb antibody effective to selectively inhibit formation of analternative complement pathway activation products C3a, C5a, and C5b-9,and activation of neutrophils, monocytes, and platelets. The anti-factorBb antibody can selectively bind Bb region of Factor B.

In an aspect of the invention, the anti-factor Bb antibody can bind to amotif in a fusion protein comprising at least one of a factor D cleavagesite of factor B, a VWF domain of factor B, or serine protease domain offactor B. The anti-factor Bb antibody does not bind the Ba motif of thefactor B. The anti-factor Bb antibody also does not prevent Factor B orBb binding to C3b/PC3b.

The anti-factor Bb antibody can be a full antibody or an antigen-bindingfragment of an anti-factor Bb antibody. The antibody can be a chimeric,deimmunized, humanized, fully human, or truncated antibody. Thefragmented antibody can include F(ab), F(ab′), F(ab)2, F(ab′)2, Fv,single chain fragment, or truncated F(ab)2 or F(ab′)2 fragment.

The anti-factor Bb antibody administered to the subject is effective toselectively inhibit the activity of alternative complement C3 convertaseC3bBb or PC3bBb, does not inhibit the classical complement pathway,reduces the levels of catalytically active PC3bBb/C3bBb complex andincreases the levels of catalytically inactive PC3bBb/C3bBb complexes,prevents the formation of additional C3b and PC3b, increases theclearance of the complex C3bBb-antifactor Bb agent via the CR1 receptorson erythrocytes, inhibit formation of anaphylatoxins C3a and C5a, andmembrane attack complex C5b-9 or sC5b-9, and prevent activation ofneutrophils, monocytes, and platelets.

The adverse effects of complement activation treated by the anti-factorB antibody can include a disease or condition selected from the groupconsisting of atherosclerosis, ischemia-reperfusion following acutemyocardial infarction, Henoch-Schonlein purpura nephritis, immunecomplex vasculitis, rheumatoid arthritis, arteritis, aneurysm, stroke,cardiomyopathy, hemorrhagic shock, crush injury, multiple organ failure,hypovolemic shock and intestinal ischemia, transplant rejection, cardiacSurgery, PTCA, spontaneous abortion, neuronal injury, spinal cordinjury, myasthenia gravis, Huntington's disease, amyotrophic lateralsclerosis, multiple sclerosis, Guillain Barre syndrome, Parkinson'sdisease, Alzheimer's disease, acute respiratory distress syndrome,asthma, chronic obstructive pulmonary disease, transfusion-related acutelung injury, acute lung injury, Goodpasture's disease, myocardialinfarction, post-cardiopulmonary bypass inflammation, cardiopulmonarybypass, septic shock, transplant rejection, xeno transplantation, burninjury, systemic lupus erythematosus, membranous nephritis, Berger'sdisease, psoriasis, pemphigoid, dermatomyositis, anti-phospholipidsyndrome, inflammatory bowel disease, hemodialysis, leukopheresis,plasmapheresis, heparin-induced extracorporeal membrane oxygenation LDLprecipitation, extracorporeal membrane oxygenation, maculardegeneration, spontaneous abortion and combinations thereof.

The present invention also relates to a method of inhibiting alternativecomplement pathway activation in a mammal. The method includesadministering to a mammal an amount of an antibody and/or fragmentthereof that specifically binds to an epitope of Bb segment of thefactor B effective to inhibit alternative complement pathway in themammal. The antibody can be monoclonal. The antibody can also bechimeric, recombinant, humanized, de-immunized, fully human, ortruncated. The antibody fragment can include F(ab), F(ab′), F(ab)2,F(ab′)2, Fv, single chain fragment, truncated F(ab)2, IgG, or truncatedIgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: factor B binding to C3b is not inhibited,the formation of C3bB is reduced, C3bBb formation is reduced, C3a andC5a production is reduced, C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, formation ofleukocyte-platelet conjugates is reduced, or Ba production is reduced.The antibody can also inhibit alternative pathway dependent rabbiterythrocyte lysis in human serum/plasma and be administered in vivo orex vivo.

The present invention further relates to a method of inhibitingalternative complement pathway activation in a mammalian host byadministering to the host a therapeutically effective amount of ananti-factor Bb antibody that specifically binds to an epitope within theserine protease domain of Bb. The antibody can be monoclonal. Theantibody can also be chimeric, recombinant, humanized, de-immunized,fully human, or truncated. The antibody fragment can include F(ab),F(ab′), F(ab)2, F(ab′)2, Fv, single chain fragment, truncated F(ab)2,IgG, or truncated IgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: factor B binding to C3b is not inhibited,the formation of C3bB is reduced, C3bBb formation is reduced, C3a andC5a production is reduced, C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, formation ofleukocyte-platelet conjugates is reduced, or Ba production is reduced.The antibody can also inhibit alternative pathway dependent rabbiterythrocyte lysis in human serum/plasma and be administered in vivo orex vivo.

The present invention still further relates to a method of inhibitingalternative complement pathway activation in a mammal by administeringto the mammal a therapeutically effective amount of an anti-factor Bbantibody that specifically binds to the catalytic triad Asp-His-Ser inthe serine protease domain of factor B and its Bb fragment. The antibodycan be monoclonal. The antibody can also be chimeric, recombinant,humanized, de-immunized, fully human, or truncated antibody. Theantibody fragment can include F(ab), F(ab′), F(ab)2, F(ab′)2, Fv, singlechain fragment, truncated F(ab)2, IgG, or truncated IgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: the formation of C3bB is reduced by way ofreduced formation of C3b, C3 convertase formation is reduced, C3a andC5a production is reduced, C5b-9/C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, or formation ofleukocyte-platelet conjugates is reduced. The antibody can also inhibitalternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma and be administered in vivo or ex vivo.

The present invention also relates to a method of inhibiting alternativecomplement pathway activation in a mammalian subject by administering tothe subject a therapeutically effective amount of the anti-factor Bbantibody that specifically binds to an epitope within the serineprotease domain of Bb. The antibody can be monoclonal. The antibody canalso be chimeric, recombinant, humanized, de-immunized, fully human, ortruncated. The antibody fragment can include F(ab), F(ab′), F(ab)2,F(ab′)2, Fv, single chain fragment, truncated F(ab)2, IgG, or truncatedIgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: the formation of C3bB is reduced by way ofreduced formation of C3b, C3 convertase formation is reduced, C3a andC5a production is reduced, C5b-9/C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, or formation ofleukocyte-platelet conjugates is reduced. The antibody can also inhibitalternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma and be administered in vivo or ex vivo.

Yet another aspect of the present invention relates to a method ofinhibiting alternative complement pathway activation in a mammal byadministering to the mammal an amount of an antibody or fragment thereofthat specifically binds to Bb and inhibits C3b oligomer formation by wayof preventing formation of additional C3b molecules which otherwisewould associate with existing C3b to form oligomers. The C3b oligomerscan contain two or more C3b monomers.

In an aspect of the invention, the antibody specifically binds to anepitope on the Bb sequence. The epitope includes at least a portion ofthe amino acid sequence of serine protease domain or VWA domain. Theanti-factor Bb binding to Bb prevents production of additional C3bmonomers.

The antibody can be monoclonal. The antibody can also be chimeric,recombinant, humanized, de-immunized, fully human, or truncated. Theantibody fragment can include F(ab), F(ab′), F(ab)2, F(ab′)2, Fv, singlechain fragment, truncated F(ab)2, IgG, or truncated IgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: the formation of C3bB is reduced by way ofreduced formation of C3b, C3 convertase formation is reduced, C3a andC5a production is reduced, C5b-9/C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, or formation ofleukocyte-platelet conjugates is reduced. The antibody can also inhibitalternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma and be administered in vivo or ex vivo.

Another aspect of the present invention relates to a method of treatingalternative pathway activation mediated by disease-related orpathological conditions. The method includes administering to the mammala therapeutically effective amount of an antibody or fragment thereofthat specifically binds to an epitope of Bb that blocks the alternativepathway activation without affecting the classical pathway activation.The antibody can be monoclonal. The antibody can also be chimeric,recombinant, humanized, de-immunized, fully human, or truncated. Theantibody fragment can include F(ab), F(ab′), F(ab)2, F(ab′)2, Fv, singlechain fragment, truncated F(ab)2, IgG, or truncated IgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: the formation of C3bB is reduced by way ofreduced formation of C3b, C3 convertase formation is reduced, C3a andC5a production is reduced, C5b-9/C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, or formation ofleukocyte-platelet conjugates is reduced. The antibody can also inhibitalternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma and be administered in vivo or ex vivo.

The disease or condition treated can be selected from the groupconsisting of atherosclerosis, ischemia-reperfusion following acutemyocardial infarction, Henoch-Schonlein purpura nephritis, immunecomplex vasculitis, rheumatoid arthritis, arteritis, aneurysm, stroke,cardiomyopathy, hemorrhagic shock, crush injury, multiple organ failure,hypovolemic shock and intestinal ischemia, transplant rejection, cardiacSurgery, PTCA, spontaneous abortion, neuronal injury, spinal cordinjury, myasthenia gravis, Huntington's disease, amyotrophic lateralsclerosis, multiple sclerosis, Guillain Barre syndrome, Parkinson'sdisease, Alzheimer's disease, acute respiratory distress syndrome,asthma, chronic obstructive pulmonary disease, transfusion-related acutelung injury, acute lung injury, Goodpasture's disease, myocardialinfarction, post-cardiopulmonary bypass inflammation, cardiopulmonarybypass, septic shock, transplant rejection, xeno transplantation, burninjury, systemic lupus erythematosus, membranous nephritis, Berger'sdisease, psoriasis, pemphigoid, dermatomyositis, anti-phospholipidsyndrome, inflammatory bowel disease, hemodialysis, leukopheresis,plasmapheresis, heparin-induced extracorporeal membrane oxygenation LDLprecipitation, extracorporeal membrane oxygenation, maculardegeneration, and combinations thereof.

The present invention further relates to an isolated antibody or antigenbinding portion thereof that includes the heavy chain variable regionsand the light chain variable regions of an antibody produced by thehybridoma cell line deposited under ATCC Accession Number PTA-8543.

The antibody can be monoclonal. The antibody can also be chimeric,recombinant, humanized, de-immunized, fully human, or truncatedantibody. The antibody fragment can include F(ab), F(ab′), F(ab)2,F(ab′)2, Fv, single chain fragment, truncated F(ab)2, IgG, or truncatedIgG.

The ratio of antibody binding to factor B can be about about 0.5:1 toabout 2:1. Administration of the antibody to the mammal can result in atleast one of the following: the formation of C3bB is reduced by way ofreduced formation of C3b, C3 convertase formation is reduced, C3a andC5a production is reduced, C5b-9/C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, or formation ofleukocyte-platelet conjugates is reduced. The antibody can also inhibitalternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma and be administered in vivo or ex vivo.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the complement pathway.

FIG. 2 is a schematic illustration of alternative complement activation.

FIG. 3 illustrates a schematic of factor B.

FIG. 4A is a schematic illustration of the mechanism of interaction ofthe anti-factor Bb monoclonal antibody with Factor B and its fragmentBb, and FIG. 4B is a schematic illustration of the mechanism ofinteraction of a prior art monoclonal antibody with Factor B and itsfragment Ba.

FIG. 5 illustrates the inactivation of PC3bBb by the monoclonal antibodyof the present invention.

FIG. 6 shows the binding of Factor B to C3b and PC3b. Properdin BoundC3b with High Affinity: Factor B has a higher affinity towards properdinbound C3b. Various concentrations of factor B were added to platescoated with C3b and Properdin-C3b. Properdin bound C3b enhances thebinding of factor B to C3b by ˜20 fold. In this assay, the Kd of bindingto C3b is ˜19.4 nM and the binding to properdin bound C3b is 1.11 nM.

FIG. 7 shows that the high affinity binding of Factor B to PC3b over C3bis not due to direct supportive binding of properdin to factor B.Rather, properdin does not bind Factor B at any of the concentrationstested.

FIG. 8 shows that factor B does not bind C3b isoforms in the presence orabsence of properdin: In this figure, increasing concentrations ofFactor B were incubated with substrate-bound iC3b, C3c and C3dg. Asshown, Factor B showed the lack of high affinity binding to C3bisoforms.

FIG. 9 illustrates making of monoclonal antibodies in mice. Monoclonalantibodies to Bb were made using standard procedure. All six mice,received the same treatment and sera from each of the six mice wasevaluated for factor B binding. This figure represents the bindingaffinity of the mouse serum to human factor B. The titer of the sera wasevaluated by incubating the factor B coated plates with mouse serumdiluted up to 1:20,000 dilution. The half maximum was evaluated byhyperbola curve fitting.

FIG. 10 illustrates inhibition of AP Dependent Hemolysis by Mice Sera:As shown, serum from only one mouse out of six used, inhibited APdependent hemolysis. This figure demonstrates that the serum of only onemouse (A3) was capable of inhibiting hemolysis of rabbit erythrocytes.In this assay normal human serum in AP buffer is incubated with rabbiterythrocytes at 37 degree in a temperature controlled ELISA platereader. As a result, AP activation, C5b-9 is formed on the erythrocytesurface causing lysis of the erythrocytes. The monoclonal antibody whichinterferes with the AP activation should prevent such lysis. Serum frommouse #A3 prevented lysis of erythrocytes. The lysis in this assay ismeasured at 700 nm.

FIG. 11 illustrates the screening of Hybridoma Supernatants for Factor Bbinding. Spleen from the selected mouse were removed and subjected tocloning to identify a clone that inhibits AP activation. These cloneswere assayed for binding to substrate-bound human factor B. In a typicalsetting, the supernatants from various clones were incubated onto FactorB coated wells. The monoclonal antibodies binding to Factor B weredetected with an HRP-conjugated goat anti-mouse secondary antibody.Clones that demonstrated an O.D. of one or greater were selected aspositives.

FIG. 12 illustrates the screening of hybridoma clones for inhibition ofAP activation via C3b formation: All clones screened in FIG. 11 weresubjected to an AP dependent C3b formation assay. Supernatants fromclones shown in FIG. 11 were mixed with 10% human serum (finalconcentration in the mixture) in AP buffer and incubated onto wellsimmobilized with LPS at 37° C. As a result, LPS will activate AP inhuman serum and causes C3b deposition. The absence of C3b deposition wastaken as a direct measure of AP inhibition. Only one clone, named 1D3was found to inhibit AP activation. This clone was subcloned severaltimes to identify a single cell population. The final clone was alsonamed as 1D3.

FIG. 13 illustrates the inhibition of AP dependent hemolysis by 1D3supernatant: 1D3 was also evaluated for AP inhibition using thepreviously described hemolysis assay. As shown, 1D3 supernatant clearlyinhibited hemolysis compared to the serum control. This clone was usedto generate anti-Bb specific monoclonal antibodies. The cell line wasdeposited with ATCC under Patent Deposit Designation PTA-8543.

FIG. 14 illustrates inhibition of AP dependent hemolysis by ascites frommouse bearing ID3 cells: The clone 1D3 was injected in mice for bulkproduction of the monoclonal antibody. Ascites was produced and testedto determine whether the monoclonal antibody in ascites fluid retainsits AP inhibitory activity. As shown, ascites fluid was diluted andmixed with rabbit erythrocytes as outlined elsewhere. Crude ascitesfluid retains the AP blocking activity.

FIG. 15 illustrates SDS-PAGE of the purified monoclonal antibody: Theantibody was purified from ascites using standard methods. As shown, theantibody (Lane 1) appears to be free from extraneous proteins.

FIG. 16 illustrates inhibition of AP dependent hemolysis by purifiedmonoclonal antibody, named NM001: This monoclonal antibody inhibitshemolysis in a dose dependent manner with nearly 100% inhibitionoccurring at 100 μg/ml concentration.

FIG. 17 illustrates NM001 binding to Human Factor B with high affinity:Increasing concentrations of NM001 were incubated in ELISA wells coatedwith factor B protein. The amount of total binding of NM001 wasdetermined using an HRP-conjugated goat anti-mouse antibody (Sigma).Optical density (O.D.) readings from this assay revealed that NM001binds factor B with high affinity. Data are presented as the meanO.D.±S.E.M. of triplicate wells of a representative experiment repeated3 times. In a typical experiment, 12 concentrations of NM001, rangingfrom 0-70 nM were used. The affinity of binding was found to be in therange of 295 pM.

FIG. 18 illustrates that purified NM001 inhibits AP dependent hemolysis:NM001 was tested for its ability to inhibit alternative pathwaydependent hemolysis of rabbit erythrocytes in normal human serum in APbuffer. The hemolysis assay was carried out as described elsewhere. Ateach concentration of NM001 a kinetic curve was generated and the endpoint readings from each curve were plotted to generate the curve shownhere. With this information, the IC50 of NM001's blocking activity wasdetermined. We found that NM001 gave an IC50 of ˜152 nM.

FIG. 19 illustrates the lack of inhibition of inhibition of Factor Bbinding to C3b or PC3b by NM001 in AP buffer using pure proteins. Asshown, NM001 at any concentration does not inhibit Factor B binding toC3b in the presence or absence of properdin. Various concentrations ofNM001 were incubated with factor B (fixed concentration) with or withoutproperdin. This solution was incubated with C3b coated plates in APbuffer.

FIG. 20 illustrates the lack of inhibition of Factor B binding to C3b orproperdin-bound C3b in AP buffer in normal human serum. Variousconcentration of NM001 were mixed with diluted human serum and incubatedwith C3b coated plates. This assay demonstrated that NM001 does notinhibit the binding of factor B to C3b (PC3b).

FIG. 21 illustrates that NM001 inhibits formation of C3b via AP. In thisassay, Normal human serum with and without NM001 was incubated withsubstrate-bound LPS. As a result of AP activation C3b is formed. NM001inhibits C3b formation in a dose dependent manner with an IC50 of around20 nM.

FIG. 22 illustrates that NM001 inhibits C5b-9 formation in human serum.C5b-9 is the terminal component of the complement cascade and isresponsible for cellular lysis. Various concentrations of NM001 wasadded to normal human serum and mixture incubated on LPS coated plates.LPS activates the alternative pathway in human serum. It is expectedthat inhibition of C3bBb activity by NM001 should inhibit downstreamevents and therefore should prevent C5b-9 formation. As shown, NM001inhibits C5b-9 formation in a dose dependent manner with highestinhibition occurring at a 20 nM concentration with an IC50 near 12-13nM.

FIG. 23 illustrates NM001 inhibition of C3b formation as shown by theloss of properdin deposition. As a result of complement activation inhuman serum, C3b is formed. The newly formed C3b associates with FactorP to form the oligomeric C3b. Detection of both C3b and properdin byspecific antibodies demonstrates that properdin deposition is inhibited.Inhibition of properdin deposition corroborated with C3b deposition.NM001 does not inhibit properdin binding to C3b or properdin binding toFactor B. As shown, NM001 effectively inhibits the formation of PC3bcomplex. The IC50 of inhibition is in pMolar range.

FIG. 24 illustrates BikacioMab binding to human Factor B with highaffinity: Bikaciomab is an F(ab′)2 fragment of the NM001 Similar toNM001, BikacioMab binds Factor B with high affinity. Variousconcentrations of BikacioMab were incubated with substrate bound factorB. The bound Factor B was detected with an HRPO-conjugated goatanti-mouse monoclonal antibody. As shown, the affinity of binding is inpM range.

FIG. 25 illustrates BikacioMab inhibition of cellular hemolysis. Theassay was conducted as described in FIGS. 10 and 16. Variousconcentration of Bikaciomab were mixed with normal human serum andincubated with rabbit erythrocytes to allow AP activation to proceed.Bikaciomab inhibited hemolysis of erythrocytes in AP buffer.

FIG. 26 illustrates that Bikaciomab does not inhibit the classicalpathway activity in Gelatin Veronal Buffer that allows activation ofboth complement pathways. Normal human serum at 1% was incubated withantibody sensitized sheep cells to allo CP activation to occur undertest conditions. Control samples without the BikacioMab additioncompletely lysed the cells. EDTA controls prevented the Lysis.BikacioMab does not inhibit CP mediated cellular lysis in concentrationrange of 1-100 μg/ml in 1% human serum. The end points following thekinetic analyses were plotted to generate the line shown in Fig.

FIG. 27 illustrates Bikaciomab effect on C3b formation in human serum.Similar to FIG. 21, various concentrations of Bikaciomab were added tonormal human serum and the mixture incubated on LPS coated plates. LPSstimulates normal human serum and activates the alternative pathway. Asa result, C3 convertase is formed which cleaves additional C3 moleculesto produce C3b. As shown, BikacioMab inhibits C3b formation in a dosedependent manner with complete inhibition occurring around 80 nMconcentration.

FIG. 28 illustrates Bikaciomab effects on C5b-9 formation in humanserum. Similar to the assay described in FIG. 22, BikacioMab inhibitsC5b-9 formation in a dose dependent manner with an IC50 of 36 nM. C5b-9is the terminal component of the complement cascade and is responsiblefor many deleterious effects when inappropriately activated.

FIG. 29 illustrates that BikacioMab inhibits C3a formation. Variousconcentrations of BikacioMab were incubated with whole human blood androtated through the tubing loop. After rotation, the plasma wasseparated and evaluated for the presence C3a using Quidel's ELISA.BikacioMab inhibits C3a formation in a dose-dependent manner.

FIG. 30 illustrates that BikacioMab inhibits C5a formation duringextracorporeal circulation of whole human blood: The effect ofBikacioMab is dose dependent.

FIG. 31 illustrates BikacioMab, inhibits C5b-9 formation in a dosedependent manner. These data are consistent with the inhibition of C3a,and C5a formation in this model of extra corporeal circulation.

FIG. 32 illustrates Bikaciomab inhibits neutrophil activation. Theactivation of Neutrophil was measured using flow cytometry approaches.An aliquot of blood sample at each concentration at the end of the 2 hrotation for extracorporeal circulation was stained with FITC-CD15 andPE-CD11b monoclonal antibodies. CD15 is a body marker and CD11b measuresexpression of CD11b, which is expressed on activated neutrophihls and isa measure of inflammation. As shown, BikacioMab inhibition of CD11b isdose dependent with a complete inhibition occurring at 100 μg/mlconcentration.

FIG. 33 illustrates BikacioMab inhibits Monocyte activation. Activatedmonocytes also express CD11b upon activation. The body marker isdifferent than what was used for neutrophils. FITC-CD14 labelsmonocytes. Bikaciomab inhibits monocyte activation in a dose dependentmanner with nearly complete inhibition occurring at around 100 μg/ml inwhole blood.

FIG. 34 illustrates BikacioMab inhibits platelet activation. Completeinhibition of platelet activation indicates that the complement is theonly mechanism of platelet activation. As shown, nearly 20 μg/ml ofBikacioMab completely prevents platelet activation. We measured plateletactivation by labeling CD62P with a PE-CD62 antibody. Platelets wereidentified using CD61 as a bosy marker Inhibition of cellular activationis consistent with the inhibition of complement activation

FIG. 35 illustrates Bikaciomab prevents TNF production. Plasma samplesfollowing tubing loop were evaluated for TNF using the assay from BDBiosciences.

FIG. 36 illustrates Bikaciomab prevents elastase production.

DETAILED DESCRIPTION OF THE INVENTION

“Antibody” or “antibody peptide(s)” refer to an intact antibody, or abinding fragment thereof that competes with the intact antibody forspecific binding. Binding fragments are produced by recombinant DNAtechniques, or by enzymatic or chemical cleavage of intact antibodies.Binding fragments include Fab, Fab′, F(ab′)₂, Fv, single-chainantibodies, truncated antibodies and F(ab′)₂ truncated antibodies. Anantibody other than a “bispecific” or “bifunctional” antibody isunderstood to have each of its binding sites identical.

The term “monoclonal” refers to an antibody that binds to a sequence ofamino acid and has a single specific epitope on its target antigen. Forexample, NM001 is a monoclonal antibody that is specific Bb domain offactor B. Because the antibody is monoclonal, it would recognize adomain/motif that contains the sequence contained in Bb (SEQ ID NO: 3).

The term “polyclonal” refers to an antibody that recognizes multipleepitope sites on a single antigen. For example, a polyclonal antibodyagainst Bb indicates that the antibody will bind several sites of theBb.

The term “epitope” includes any protein determinant capable of specificbinding to an immunoglobulin. Epitope determinants usually consist ofchemically active surface groupings of molecules such as amino acids orsugar side chains and usually have specific three-dimensional structuralcharacteristics, as well as specific charge characteristics.

The terms “oligomer” and “polymer” are used interchangeable. The terms“oligomer” and “polymer” refer to the association of more than onemonomer of a specific protein, peptide, or peptide fragments. The terms“oligomer” and “polymer” in this invention specifically relates to theability of properdin protein monomers to form protein complexes with itor with other proteins.

The term “agent” is used herein to denote a chemical compound, a mixtureof chemical compounds, a biological macromolecule, or an extract madefrom biological materials.

The terms “patient,” “mammalian host,” “mammalian subject,” “subject”,and the like are used interchangeably herein, and refer to mammals,including human and veterinary subjects.

As used herein, the terms “treatment,” “treating,” and the like, referto obtaining a desired pharmacologic and/or physiologic effect. Theeffect may be prophylactic in terms of completely or partiallypreventing a disease or symptom thereof and/or may be therapeutic interms of a partial or complete cure for a disease and/or adverse affectattributable to the disease. “Treatment,” as used herein, covers anytreatment of a disease in a mammal, particularly in a human, andincludes: (a) preventing the disease from occurring in a subject whichmay be predisposed to the disease or at risk of acquiring the diseasebut has not yet been diagnosed as having it; (b) inhibiting the disease,i.e., arresting its development; and (c) relieving the disease, i.e.,causing regression of the disease.

The term “a disease or disorder associated with the alternativecomplement pathway,” as used herein, refers to a disease or disordercaused, directly or indirectly, by activation of the alternativecomplement pathway, a disease or disorder that is mediated, directly orindirectly, by one or more components of the alternative complementpathway, or a product generated by the alternative complement pathway.The term also refers to a disease or disorder that is exacerbated by oneor more components of the alternative complement pathway, or a productgenerated by the alternative complement pathway.

The term “knockout” refers to the technique in which a specific gene(s)are removed from a target animal. This technique is usually applied torodents in which the gene of interest is removed via homologousrecombination of an empty vector with the native animal chromosome. Thetechnique works by swapping the animal's chromosome containing the genewith the empty vector containing a marker or random DNA sequences. Thismethod results in an animal that is deficient of the gene of interest.The present invention would utilize this technique to generateantibodies against an antigen that is removed from the animal's genometo enhance generation of antibodies.

It is to be understood that the terminology used herein is fordescribing particular embodiments only, and is not intended to belimiting, since the scope of the present invention will be limited onlyby the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges, and are encompassed within the invention, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the invention.

The present invention relates to a method of a method of inhibitingalternative complement pathway activation in a mammal, inhibiting theadverse effects of alternative complement pathway activation products,and/or treating alternative pathway activation mediated bydisease-related or pathological conditions. The method includesadministering to a mammal an anti-factor Bb agent that inhibits thefunction of C3b/PC3b bound Bb, inhibits the function of PC3bBb byblocking its proteolytic activity, inhibits the factor D cleavage offactor B, inhibits the formation of C3a, C3b, C5a, C5b-9, and sC5b-9,inhibits the formation of C3bBb and PC3bBb, inhibiting the formation ofBa, inhibits the formation of Bb, inhibits the properdin-inducedoligomerization of C3b, and inhibits the activation of neutrophils,monocytes, and platelets in clinical conditions where the diseasepathology is complement-mediated.

Factor B is a 90 kDa protein that can have an amino acid sequence of SEQID NO: 1. Factor B consists of three domains (FIG. 3): a three-modulecomplement control protein (CCP1, CCP2, and CCP3), a von Willebrandfactor A domain (e.g., SEQ ID NO: 5), and a C-terminal serine protease(SP) domain (e.g., SEQ ID NO: 6) that adopts a default inactive(zymogen) conformation. The interaction between factor B andsurface-bound C3b triggers a conformational change in factor B thatultimately creates the “C3 convertase” (PC3bBb) of the alternativecomplement pathway. The activation of the alternative pathway ofcomplement (AP) hinges on a Magnesium ion-enhanced interaction betweenfactor B and C3b. Upon binding, factor B is rendered susceptible toproteolytic cleavage by factor D, forming fragments Ba (30 kDa) (e.g.,SEQ ID NO: 2) and Bb (60 kDa) (e.g., SEQ ID NO: 3). Bb, in associationwith C3b, comprises the AP C3 convertase. This complex has serineprotease activity and functions to cleave native C3 into C3a and C3b.

Factor B is activated through an assembly process: it bindssurface-bound C3b after which it is cleaved by factor D into fragmentsBa (residues 26-234; SEQ ID NO: 2) and Bb (residues 235-739 SEQ ID NO:3). Fragment Ba dissociates from the complex, leaving behind thealternative pathway C3 convertase complex C3b-Bb, which cleaves C3 intoC3a and C3b. This protease complex is intrinsically instable. Oncedissociated from the complex, Bb cannot reassociate with C3b. Theproenzyme factor B consists of three N-terminal complement controlprotein (CCP: 1, 2, and 3) domains, connected by a 45-residue linker(SEQ ID NO: 4) to a VWA domain and a C-terminal serine protease (SP)domain, which carries the catalytic center triad (ASP-HIS-SER). The VWAand SP domains form fragment Bb, and CCP1 through CCP3 and the linkerform fragment Ba. Binding of factor B to C3b depends on elements infragment Ba and the Mg2+-dependent metal ion-dependent adhesion site(MIDAS) motif in the VWA domain of fragment Bb.

In both intact Factor B and Bb, serine protease domain is exposed andthe catalytic site is freely accessible to small substrates. The twostructures differ markedly in the orientation of the VWA-SP region. Inactive state, the cleaved Bb exposes the catalysis site even further andis fully functional to now allow cleavage of further C3 molecules intoC3a and C3b Inhibition of Bb activity by the anti-factor Bb agentprevents the formation of C3a and C3b.

In accordance with an aspect of the invention, the anti-factor Bb agentcan include an anti-factor Bb antibody that is directed to orspecifically binds to Bb domain of factor B. The anti-factor Bb antibodyof this invention binds the Bb fragments, does not bind Ba fragment,does not inhibit the factor B binding to C3b, inhibits C3b production,inhibits C3a, C5a, and C5b-9 formation and inhibits lysis of rabbiterythrocytes. FIG. 4A is schematic illustration of mechanisms of actionthe anti-factor B antibody. FIG. 4A shows that the anti-factor Bbantibody can inhibit the alternative pathway by binding the Bb domain innative Factor B and blocking the Factor D cleavage, binding thecatalytic triad in the serine protease domain and preventing its actionon C3 cleavage and hence halting C3b production, or binding thecatalytic triad and locking the conformation such that cleavage ofFactor B cannot occur. In contrast, as illustrated in FIG. 4B, prior artanti-Ba antibody does not bind the Bb segment and is involved only inFactor B binding to C3b. The anti-factor Bb antibody of presentinvention, however, does not inhibit the binding of Factor B to C3b.

The anti-factor Bb antibody of the present invention can also inhibitoligomerization of C3b. The molecular weight of native C3 is in theorder of 190 kDa, upon cleavage by the convertase, C3 is converted intoa C3a (10 kDa) and C3b (180 kDa). This C3b molecule has high affinityfor properdin oligomers, as a result forms a complex containing 3 C3bmolecules attached to a properdin trimer. Anti-factor Bb monoclonalantibodies of the present invention prevent formation of additionalmolecules of C3b and therefore result in a complex where C3b oligomerwill not form. If C3b formation is completely prevented properdin willfloat alone without any C3b attached. Properdin does not bind C3 or theisoforms of C3b.

In another aspect, the anti-factor Bb antibody of the present inventioncan bind to the serine protease domain and particularly the catalytictriad of serine protease of the Bb region. The mechanism of action ofthe anti-factor Bb antibody once bound to the serine protease domain isshown in FIG. 5. The serine protease domain forms the third and the lastdomain of intact factor B. The serine protease domain carries thecatalytic site which is solely responsible for C3 cleavage. While thecatalytic site is exposed in both intact factor B and the Bb fragment,it becomes active only after the Ba is cleaved off by factor D.

The anti-factor Bb antibody of the present invention can bind thecatalytic triad and prevent its activity by either locking the inactiveconformation in place or by binding to the region where factor D cleavesthe factor B. The development of an anti-factor Bb antibody inaccordance with the present invention that specifically recognizes thecatalytic triad is a surprising discovery because limited number ofhighly target specific protease inhibitory antibodies have beendiscovered. The anti-factor Bb antibody can be highly target specific inthat it only cross reacts to human factor B and shows no crossreactivity to rat, rabbit, guinea pig, dog, baboon, rhesus, andcynomologous monkey. These findings are of high importance and suggeststhat anti-factor Bb antibody is a highly target specific antibody. Forsuch antibodies, animal data is not required for moving into theclinical trial for human safety and efficacy.

In another aspect of the invention, the anti-factor Bb antibody can bespecific to inhibiting the alternative pathway and not inhibit theclassical pathway, which is generally required for host defense againstinfection. The anti-factor Bb antibody can also inhibit C3a, C5a, andC5b-9 and cellular activation. Both C3a and C5a are potentanaphylatoxins that are generated during the AP activation. Regardlessof the trigger/initiator of the AP, if C3a, C5a and C5b-9 are formed inexcessive amounts above control levels, damage to cellular systemsoccurs. Neutrophils bear the C5a receptor and therefore respond tocompounds that prevent C5a production or antibodies that neutralize theC5a or the receptor antagonists that prevent receptor attack by C5a.Similarly, platelets have the C3a receptors and therefore agents thatprevent/neutralize C3a activity would prevent platelet activation.Monocytes have C3a receptors and upon activation release “TNF” and“IL-1” which have been implicated in inflammatory diseases such asarthritis. Secretory components such as neutrophil elastase, TNF, andIL-1 have been defined as the markers of inflammation. In additionactivated neutrophils, monocytes and platelets orchestrate theinflammatory responses by forming leukocyte-platelet conjugates. In anumber of clinical diseases, all these cell types are known.

Anti-factor Bb antibodies of the present invention can include murinehuman anti-factor Bb monoclonal antibodies, and compositions comprisingthe antibodies. The anti-factor Bb antibody can be produced by anantibody-producing hybridoma. Chimeric, de-immunized, single chain,truncated, fully human and humanized versions of the anti-factor Bbantibody can be generated by those skilled in the art.Human/humanized/chimerized anti-factor Bb antibody avoids problemsassociated with rodent antibodies, i.e., adverse reactions in humans,such as hypersensitivity reactions, including urticaria, dyspnea,hypotension, anaphylaxis, and the like.

An example of an anti-factor Bb antibody in accordance with the presentinvention that specifically binds to the Bb region was isolated asdescribed in the Examples. The Examples of the present applicationdisclose an anti-factor Bb antibody identified as NM001 that is producedby the hybridoma cell line 1D3 deposited under ATCC Accession NumberPTA-8543. NM001 and an F(ab)2 fragment of NM001 (Bikaciomab)surprisingly bind in the factor Bb region of the molecule and show noreactivity to the peptide Ba. As shown in the Examples, NM001 and theF(ab)2 fragment do not cross react with rat, mouse, rabbit, dog, pig,baboon sera. However, NM001 and the F(ab)2 fragment exclusively crossreact with Cynomologus and Human thereby making it a highly specific tohumans. NM001 and the F(ab)2 fragment were found to inhibit C3bproduction, inhibit C3a production, inhibit C5a production, inhibitC5b-9 production, inhibit sC5b-9 production, inhibit TNF production,inhibit Elastase production, inhibit neutrophil activation, inhibitmonocyte activation, and inhibit platelet activation.

Another aspect of the invention relates to antibodies that bind to thesame epitope on Bb as NM001. Such antibodies can be identified based ontheir ability to cross-compete with NM001 in standard Bb binding assays.The ability of a test antibody to inhibit the binding of NM001 to Bbdemonstrates that the test antibody can compete with NM001 for bindingto Bb and thus binds to the same epitope on Bb as NM001. In an aspect ofthe invention, the antibody that binds to the same epitope on Bb asNM001 is a human monoclonal antibody.

In yet another aspect, the anti-factor Bb antibody of the invention cancomprise heavy and light chain variable regions comprising amino acidsequences that are homologous to the amino acid sequences of thepreferred antibodies described herein, while retaining the desiredfunctional properties of the anti-factor Bb antibodies of the invention.For example, the invention provides an isolated monoclonal antibody, orantigen binding portion thereof, comprising a heavy chain variableregion and a light chain variable region, wherein: (a) the heavy chainvariable region comprises an amino acid sequence that is at least 80%homologous to the amino acid sequence of the heavy chain of NM001 (b)the light chain variable region comprises an amino acid sequence that isat least 80% homologous to the amino acid sequence of the light chain ofNM001; and (c) the antibody specifically binds to the Bb region offactor B.

In various aspects, the antibody can be, for example, a human antibody,a humanized antibody or a chimeric antibody. In other aspects, the VHand/or VL amino acid sequences may be 85%, 90%, 95%, 96%, 97%, 98% or99% homologous to the sequences set forth above. An antibody having VHand VL regions having high (i.e., 80% or greater) homology to the VH andVL regions of the sequences set forth above, can be obtained bymutagenesis (e.g., site-directed or PCR-mediated mutagenesis) of nucleicacid molecules the heavy and light chain of NM001, followed by testingof the encoded altered antibody for retained function (i.e., thefunctions set forth in (c) and (d) above) using the functional assaysdescribed herein.

As used herein, the percent homology between two amino acid sequences isequivalent to the percent identity between the two sequences. Thepercent identity between the two sequences is a function of the numberof identical positions shared by the sequences (i.e., % homology=# ofidentical positions/total # of positions×100), taking into account thenumber of gaps, and the length of each gap, which need to be introducedfor optimal alignment of the two sequences. The comparison of sequencesand determination of percent identity between two sequences can beaccomplished using a mathematical algorithm, as described in thenon-limiting examples below.

In certain aspects, an antibody of the invention can include a heavychain variable region comprising CDR1, CDR2 and CDR3 sequences and alight chain variable region comprising CDR1, CDR2 and CDR3 sequences,wherein one or more of these CDR sequences comprise specified amino acidsequences based on the preferred antibodies described herein (e.g.,NM001) or conservative sequence modification thereof. As used herein,the term “conservative sequence modifications” is intended to refer toamino acid modifications that do not significantly affect or alter thebinding characteristics of the antibody containing the amino acidsequence. Such conservative modifications include amino acidsubstitutions, additions and deletions. Modifications can be introducedinto an antibody of the invention by standard techniques known in theart, such as site-directed mutagenesis and PCR-mediated mutagenesis.Conservative amino acid substitutions are ones in which the amino acidresidue is replaced with an amino acid residue having a similar sidechain. Families of amino acid residues having similar side chains havebeen defined in the art. These families include amino acids with basicside chains (e.g., lysine, arginine, histidine), acidic side chains(e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g.,glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine,tryptophan), nonpolar side chains (e.g., alanine, valine, leucine,isoleucine, proline, phenylalanine, methionine), beta-branched sidechains (e.g., threonine, valine, isoleucine) and aromatic side chains(e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, one ormore amino acid residues within the CDR regions of an antibody of theinvention can be replaced with other amino acid residues from the sameside chain family and the altered antibody can be tested for retainedfunction (i.e., the functions set forth in (c) through (j) above) usingthe functional assays described herein.

An antibody of the invention further can be prepared using an antibodyhaving one or more of the VH and/or VL sequences disclosed herein asstarting material to engineer a modified antibody, which modifiedantibody may have altered properties from the starting antibody. Anantibody can be engineered by modifying one or more residues within oneor both variable regions (i.e., VH and/or VL), for example within one ormore CDR regions and/or within one or more framework regions.Additionally or alternatively, an antibody can be engineered bymodifying residues within the constant region(s), for example to alterthe effector function(s) of the antibody.

One type of variable region engineering that can be performed is CDRgrafting. Antibodies interact with target antigens predominantly throughamino acid residues that are located in the six heavy and light chaincomplementarity determining regions (CDRs). For this reason, the aminoacid sequences within CDRs are more diverse between individualantibodies than sequences outside of CDRs. Because CDR sequences areresponsible for most antibody-antigen interactions, it is possible toexpress recombinant antibodies that mimic the properties of specificnaturally occurring antibodies by constructing expression vectors thatinclude CDR sequences from the specific naturally occurring antibodygrafted onto framework sequences from a different antibody withdifferent properties. Thus, such antibodies contain the VH and VL CDRsequences of NM001 may contain different framework sequences from theseantibodies.

Another type of variable region modification is to mutate amino acidresidues within the VH and/or VK CDR1, CDR2 and/or CDR3 regions tothereby improve one or more binding properties (e.g., affinity) of theantibody of interest. Site-directed mutagenesis or PCR-mediatedmutagenesis can be performed to introduce the mutation(s) and the effecton antibody binding, or other functional property of interest, can beevaluated in in vitro or in vivo assays as described herein and providedin the Examples. Conservative modifications (as discussed above) areintroduced. The mutations may be amino acid substitutions, additions ordeletions, but are preferably substitutions. Moreover, typically no morethan one, two, three, four or five residues within a CDR region arealtered.

Anti-factor Bb monoclonal antibodies can be prepared by standard methodswell known in the art. For example, rodents (e.g. mice, rats, hamsters,and guinea pigs) can be immunized either with factor B, or factor Bbpurified from human plasma or urine or with recombinant factor B or itsfragments expressed by either eukaryotic or prokaryotic systems.Antibodies specific to factor Bb can be identified by selecting thosethat do not bind the Ba. The antibody product of the present inventiondoes not bind the Ba region of the protein. Other animals can also beused for immunization, e.g. non-human primates, transgenic miceexpressing human immunoglobulins, and severe combined immunodeficientmice transplanted with human B-lymphocytes. Hybridoma can be generatedby conventional procedures well known in the art by fusing B lymphocytesfrom the immunized animals with myeloma cells (e.g. Sp2/0 and NS0). Inaddition, anti-factor Bb antibodies can be generated by screening ofrecombinant single-chain F_(v) or F_(ab) libraries from human Blymphocytes in phage-display systems. The specificity of the MoAbs tohuman factor Bb can be tested by enzyme linked immunosorbent assay(ELISA).

In the antibody molecule, there are four chains. The amino-terminalportion of each chain includes a variable region of 100 to 110 aminoacids responsible for antigen recognition. The carboxyl-terminal portionof each chain defines a constant region primarily responsible foreffector function. Thus, an intact antibody has two binding sites.Except in bifunctional or bispecific antibodies, the two binding sitesare the same. A bispecific or bifunctional antibody is an artificialhybrid antibody having two different heavy/light chain pairs and twodifferent binding sites. Bispecific antibodies can be produced by avariety of methods including fusion of hybridomas or linking of Fab′fragments. Production of bispecific antibodies can be a relatively laborintensive process compared with production of conventional antibodiesand yields and degree of purity are generally lower for bispecificantibodies. Bispecific antibodies do not exist in the form of fragmentshaving a single binding site (e.g., Fab, Fab′, and Fv).

Human antibodies can be prepared that avoid certain of the problemsassociated with antibodies that possess murine or rat variable and/orconstant regions. An important practical application of such a strategyis the “humanization” of the mouse humoral immune system. Introductionof human immunoglobulin (Ig) loci into mice in which the endogenous IgGgenes have been inactivated offers the opportunity to study themechanisms underlying programmed expression and assembly of antibodiesas well as their role in B-cell development. Furthermore, such astrategy could provide an ideal source for production of fully humanmonoclonal antibodies (MoAbs)—an important milestone towards fulfillingthe promise of antibody therapy in human disease. Fully human antibodiesare expected to minimize the immunogenic and allergic responsesintrinsic to mouse or mouse-derivatized MoAbs and thus to increase theefficacy and safety of the administered antibodies. The use of fullyhuman antibodies can be expected to provide a substantial advantage inthe treatment of chronic and recurring human diseases, such asinflammation, autoimmunity, and cancer, which require repeated antibodyadministrations.

One approach towards this goal is to engineer mouse strains deficient inmouse antibody production with large fragments of the human IgG loci inanticipation that such mice would produce a large repertoire of humanantibodies in the absence of mouse antibodies. Large human IgG fragmentswould preserve the large variable gene diversity as well as the properregulation of antibody production and expression. By exploiting themouse machinery for antibody diversification and selection and the lackof immunological tolerance to human proteins, the reproduced humanantibody repertoire in these mouse strains should yield high affinityantibodies against any antigen of interest, including human antigens.Using the hybridoma technology, antigen-specific human MoAbs with thedesired specificity could be readily produced and selected.

Human anti-mouse antibody (HAMA) responses: While chimeric antibodieshave a human constant region and a murine variable region, it isexpected that certain human anti-chimeric antibody (HACA) responses willbe observed, particularly in chronic or multi-dose utilizations of theantibody. Thus, it would be desirable to provide fully human antibodiesagainst Bb in order to vitiate concerns and/or effects of HAMA or HACAresponse.

Humanization and Display Technologies

As was discussed above in connection with human antibody generation,there are advantages to producing antibodies with reducedimmunogenicity. To a degree, this can be accomplished in connection withtechniques of humanization and display techniques using appropriatelibraries. It will be appreciated that murine antibodies or antibodiesfrom other species can be humanized or primatized using techniques wellknown in the art.

Antibody fragments, such as Fv, F(ab′)₂ and Fab may be prepared bycleavage of the intact protein, e.g. by protease or chemical cleavage.Alternatively, a truncated gene is designed. For example, a chimericgene encoding a portion of the F(ab′)₂ fragment would include DNAsequences encoding the CH1 domain and hinge region of the H chain,followed by a translational stop codon to yield the truncated molecule.

Further, human antibodies or antibodies from other species can begenerated through display-type technologies, including, withoutlimitation, phage display, retroviral display, ribosomal display, andother techniques, using techniques well known in the art and theresulting molecules can be subjected to additional maturation, such asaffinity maturation, as such techniques are well known in the art.

Additional Criteria for Antibody Therapeutics

As discussed herein, the function of a subject anti-factor Bb antibodyappears important to at least a portion of its mode of operation. Byfunction, we mean, by way of example, the activity of the anti-factor Bbantibody in inhibiting the alternative complement pathway, e.g., asubject anti-factor Bb antibody exhibits one or more of the followingproperties: (a) inhibiting the function of C3b/PC3b bound Bb; (b)inhibiting the function of PC3bBb by blocking its proteolytic activity,(c) inhibiting the factor D cleavage of factor B, (d) inhibiting theformation of C3a, C3b, C5a, C5b-9, and sC5b-9, (e) inhibiting theformation of C3bBb and PC3bBb, (f) inhibiting the formation of Ba, (g)inhibiting the formation of Bb, (h) inhibiting the properdin-inducedoligomerization of C3b, and (i) inhibiting the activation ofneutrophils, monocytes, and platelets

Design and Generation of Other Therapeutics

Other therapeutic modalities besides antibody moieties can be designedusing the anti-factor Bb antibodies of the present invention. Suchmodalities include, without limitation, advanced antibody therapeutics,such as bispecific antibodies, immunotoxins, and radiolabeledtherapeutics, generation of peptide therapeutics, gene therapies,particularly intrabodies, antisense therapeutics, and small molecules.In connection with the generation of advanced antibody therapeutics,where complement fixation is a desirable attribute, it may be possibleto sidestep the dependence on complement for cell killing usingbispecifics, immunotoxins, or radiolabels, for example.

Bispecific antibodies can be generated that comprise (i) two antibodiesone with a specificity to Bb and another to a second molecule that areconjugated together, (ii) a single antibody that has one chain specificto Bb and a second chain specific to a second molecule, or (iii) asingle chain antibody that has specificity to Bb and the other molecule.Such bispecific antibodies can be generated using techniques that arewell known for example, in connection with (i) and (ii) and inconnection with (iii).

In connection with the generation of therapeutic peptides, through theutilization of structural information related to Bb and antibodiesthereto, such as the antibodies of the invention (as discussed below inconnection with small molecules) or screening of peptide libraries,therapeutic peptides can be generated that are directed against Bb.

Assuming that the Bb molecule (or a form, such as a splice variant oralternate form) is functionally active in a disease process, it willalso be possible to design gene and antisense therapeutics theretothrough conventional techniques. Such modalities can be utilized formodulating the function of Bb.

Therapeutic Administration and Formulations

It will be appreciated that the therapeutic anti-factor Bb antibodies inaccordance with the invention can be administered suitable carriers,excipients, and other agents that are incorporated into formulations toprovide improved transfer, delivery, tolerance, and the like. Theseformulations include, for example, powders, pastes, ointments, jellies,waxes, oils, lipids, lipid (cationic or anionic) containing vesicles(such as Lipofectin), DNA conjugates, anhydrous absorption pastes,oil-in-water and water-in-oil emulsions, emulsions carbowax(polyethylene glycols of various molecular weights), semi-solid gels,and semi-solid mixtures containing carbowax. Any of the foregoingmixtures may be appropriate in treatments and therapies in accordancewith the present invention, if the active ingredient in the formulationis not inactivated by the formulation and the formulation isphysiologically compatible and tolerable with the route ofadministration.

Therapeutic Uses

Anti-factor Bb antibodies can be used to treat diseases where APparticipates in disease pathology. The anti-factor Bb antibodies canalso be used in the treatment of many immunological disorders, eitherdirect, such as anaphylactic shock, rheumatoid arthritis, and the like,or secondary ones resulting from primary clinical conditions such ascardiopulmonary bypass inflammation, burn injury, and the like. Thediseases treated by anti-factor Bb antibodies include, but are notlimited to myocardial infarction, ischemia/reperfusion injury; vascularstenosis or post-angioplasty restenosis; stroke; acute respiratorydistress syndrome (ARDS); sepsis; burn injury; cardiopulmonary bypassinflammation; extracorporeal circulation such as hemodialysis,plasmapheresis, plateletpheresis, leukopheresis, extracorporeal membraneoxygenation (ECMO), or heparin-induced extracorporeal LDL precipitation(HELP); allergic response to the use of radiographic contrast media;transplant rejection; other inflammatory conditions andautoimmune/immune complex diseases that are closely associated withcomplement activation, such as multiple sclerosis, myasthemia gravis,pancreatitis, rheumatoid arthritis, Alzheimer's disease, asthma,spontaneous abortion, pain, neuronal and nerve cord injury, thermalinjury, anaphylactic shock, bowel inflammation, urticaria, angioedema,vasculitis, and Sjogren's syndrome, lupus erythromatosus, membranousnephritis, and dermatomysitis.

Treatment Methods

The methods generally involve administering to a mammalian subject inneed thereof an effective amount of a subject antibody (i.e.,anti-factor Bb antibody). An “effective amount” of a subject antibody isan amount that is effective to reduce the production and/or level of apolypeptide generated following activation of the alternative complementpathway by at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, or more.

A subject antibody is administered to an individual in a formulationwith a pharmaceutically acceptable excipient(s). A wide variety ofpharmaceutically acceptable excipients are known in the art and need notbe discussed in detail herein.

The pharmaceutically acceptable excipients, such as vehicles, adjuvants,carriers or diluents, are readily available to the public. Moreover,pharmaceutically acceptable auxiliary substances, such as pH adjustingand buffering agents, tonicity adjusting agents, stabilizers, wettingagents and the like, are readily available to the public.

In the subject methods, a subject antibody may be administered to thehost using any convenient means capable of resulting in the desiredtherapeutic effect. Thus, the antibody can be incorporated into avariety of formulations for therapeutic administration. Moreparticularly, a subject antibody can be formulated into pharmaceuticalcompositions by combination with appropriate, pharmaceuticallyacceptable carriers or diluents, and may be formulated into preparationsin solid, semi-solid, liquid or gaseous forms, such as tablets,capsules, powders, granules, ointments, solutions, suppositories,injections, inhalants and aerosols.

As such, administration of a subject antibody can be achieved in variousways, including oral, buccal, rectal, parenteral, intraperitoneal,intradermal, subcutaneous, intramuscular, transdermal, intranasal,pulmonary, intratracheal, etc., administration.

In pharmaceutical dosage forms, the agents may be administered in theform of their pharmaceutically acceptable salts, or they may also beused alone or in appropriate association, as well as in combination,with other pharmaceutically active compounds. The following methods andexcipients are merely exemplary and are in no way limiting.

A subject antibody can be formulated into preparations for injection bydissolving, suspending or emulsifying them in an aqueous or nonaqueoussolvent, such as vegetable or other similar oils, synthetic aliphaticacid glycerides, esters of higher aliphatic acids or propylene glycol;and if desired, with conventional additives such as solubilizers,isotonic agents, suspending agents, emulsifying agents, stabilizers andpreservatives.

Unit dosage forms for injection or intravenous administration maycomprise the inhibitor(s) in a composition as a solution in sterilewater, normal saline or another pharmaceutically acceptable carrier.

The term “unit dosage form,” as used herein, refers to physicallydiscrete units suitable as unitary dosages for human and animalsubjects, each unit containing a predetermined quantity of a subjectantibody calculated in an amount sufficient to produce the desiredeffect in association with a pharmaceutically acceptable diluent,carrier or vehicle.

A subject antibody is administered to an individual at a frequency andfor a period of time so as to achieve the desired therapeutic effect.For example, a subject antibody is administered once per month, twiceper month, three times per month, every other week (qow), once per week(qw), twice per week (biw), three times per week (tiw), four times perweek, five times per week, six times per week, every other day (qod),daily (qd), twice a day (qid), or three times a day (tid), orsubstantially continuously, or continuously, over a period of timeranging from about one day to about one week, from about two weeks toabout four weeks, from about one month to about two months, from abouttwo months to about four months, from about four months to about sixmonths, or longer.

Combination Therapy

The anti-factor Bb antibody will in some embodiments be administered inan effective amount in combination therapy with a second therapeuticagent. Examples of second therapeutic agents include, but are notlimited to, anti-inflammatory agents; agents used for the treatment ofcardiovascular disorders; steroidal anti-inflammatory agents; and thelike.

Examples of anti-inflammatory agents include, but are not limited to,non-steroidal anti-inflammatory drugs (NSAIDs) acetaminophen,salicylate, acetyl-salicylic acid (aspirin, diflunisal), ibuprofen,Motrin, Naprosyn, Nalfon, and Trilisate, indomethacin, glucametacine,acemetacin, sulindac, naproxen, piroxicam, diclofenac, benoxaprofen,ketoprofen, oxaprozin, etodolac, ketorolac tromethamine, ketorolac,nabumetone, and the like, and mixtures of two or more of the foregoing.Other suitable anti-inflammatory agents include methotrexate.

Examples of steroidal anti-inflammatory agents include, but are notlimited to, hydrocortisone, prednisone, prednisolone,methylprednisolone, dexamethasone, betamethasone, and triamcinolone.

Agents for cardiovascular indications can include GP IIb-IIIa inhibitorssuch as INTEGRILIN (eptifibatide); aprotinin; REOPRO (abciximab); andthe like.

Other second therapeutic agents can include beta adrenergics whichinclude bronchodilators including albuterol, isoproterenol sulfate,metaproterenol sulfate, terbutaline sulfate, pirbuterol acetate andsalmeterol formotorol; steroids including beclomethasone dipropionate,flunisolide, fluticasone, budesonide and triamcinolone acetonide.

Anti-inflammatory drugs used in connection with the treatment ofrespiratory diseases include steroids such as beclomethasonedipropionate, triamcinolone acetonide, flunisolide and fluticasone.Other examples of anti-inflammatory drugs include cromoglycates such ascromolyn sodium. Other respiratory drugs, which would qualify asbronchodilators, include anticholenergics including ipratropium bromide.Antihistamines include, but are not limited to, diphenhydramine,carbinoxamine, clemastine, dimenhydrinate, pryilamine, tripelennamine,chlorpheniramine, brompheniramine, hydroxyzine, cyclizine, meclizine,chlorcyclizine, promethazine, doxylamine, loratadine, and terfenadine.Particular

anti-histamines include rhinolast (Astelin), claratyne (Claritin),claratyne D (Claritin D), telfast (Allegra), zyrtec, and beconase.

In some embodiments, the anti-factor Bb antibody is administeredconcurrently with a second therapeutic agent. As used herein, the term“concurrently” indicates that the subject antibody and the secondtherapeutic agent are administered separately and are administeredwithin about 5 seconds to about 15 seconds, within about 15 seconds toabout 30 seconds, within about 30 seconds to about 60 seconds, withinabout 1 minute to about 5 minutes, within about 5 minutes to about 15minutes, within about 15 minutes to about 30 minutes, within about 30minutes to about 60 minutes, within about 1 hour to about 2 hours,within about 2 hours to about 6 hours, within about 6 hours to about 12hours, within about 12 hours to about 24 hours, or within about 24 hoursto about 48 hours of one another.

In some embodiments, the anti-factor Bb antibody is administered duringthe entire course of treatment with the second therapeutic agent. Inother embodiments, a subject antibody is administered for a period oftime that is overlapping with that of the treatment with the secondtherapeutic agent, e.g., the antibody treatment can begin before thetreatment with the second therapeutic agent begins and end before thetreatment with the second therapeutic agent ends; the antibody treatmentcan begin after the treatment with the second therapeutic agent beginsand end after the antibody treatment ends; the antibody treatment canbegin after the treatment with the second therapeutic agent begins andend before the treatment with the second therapeutic agent ends; orantibody treatment can begin before the treatment with the secondtherapeutic agent begins and end after the treatment with the secondtherapeutic agent ends.

Subjects for Treatment

Subjects that can be treated with the anti-factor Bb antibody andcombination therapies of the present invention include individualssuffering from one or more of the following disorders: atherosclerosis,ischemia-reperfusion following acute myocardial infarction,Henoch-Schonlein purpura nephritis, immune complex vasculitis,rheumatoid arthritis, arteritis, aneurysm, stroke, cardiomyopathy,hemorrhagic shock, crush injury, multiple organ failure, hypovolemicshock and intestinal ischemia, transplant rejection, cardiac Surgery,PTCA, spontaneous abortion, neuronal injury, spinal cord injury,myasthenia gravis, Huntington's disease, amyotrophic lateral sclerosis,multiple sclerosis, Guillain Barre syndrome, Parkinson's disease,Alzheimer's disease, acute respiratory distress syndrome, asthma,chronic obstructive pulmonary disease, transfusion-related acute lunginjury, acute lung injury, Goodpasture's disease, myocardial infarction,post-cardiopulmonary bypass inflammation, cardiopulmonary bypass, septicshock, transplant rejection, xeno transplantation, burn injury, systemiclupus erythematosus, membranous nephritis, Berger's disease, psoriasis,pemphigoid, dermatomyositis, anti-phospholipid syndrome, inflammatorybowel disease, hemodialysis, leukopheresis, plasmapheresis,heparin-induced extracorporeal membrane oxygenation LDL precipitation,extracorporeal membrane oxygenation, and macular degeneration.

In an a particular aspect of the invention, subjects that can be treatedwith a subject method include individuals suffering from one or more ofthe following disorders:

post-cardiopulmonary bypass inflammation, myocardial infarction, stroke,acute respiratory distress syndrome (ARDS), septic shock, transplantrejection, burn injury, multiple sclerosis, myasthenia gravis,cardiovascular disorders, and rheumatoid arthritis. Subjects suitablefor treatment with a subject method also include individuals sufferingfrom any inflammatory disorder, including, but not limited to, systemiclupus erythematosus, membranous nephritis, pemphigoid, dermatomyositis,and anti-phospholipid syndrome. Subjects suitable for treatment alsoinclude subjects undergoing renal dialysis.

Incorporation by Reference

All references cited herein, including patents, patent applications,papers, textbooks, and the like, and the references cited therein, tothe extent that they are not already, are hereby incorporated herein byreference in their entirety. In addition, the following references arealso incorporated by reference herein in their entirety, including thereferences cited in such references:

Equivalents

The foregoing description and Examples detail certain preferredembodiments of the invention and describes the best mode contemplated bythe inventors. It will be appreciated, however, that no matter howdetailed the foregoing may appear in text, the invention may bepracticed in many ways and the invention should be construed inaccordance with the appended claims and any equivalents thereof.

EXAMPLES

The examples which follow are presented to describe preferredembodiments and utilities of the invention and are not meant to limitthe invention unless otherwise stated in the claims appended hereto. Thedescription is intended as a non-limiting illustration, since manyvariations will become apparent to those skilled in the art in viewthereof. It is intended that all such variation within the scope andspirit of the appended claims be embraced thereby. Changes can be madein the composition, operation, and arrangement of the method of thepresent invention described herein without departing from the conceptand scope of the invention as defined in the claims.

Unless stated otherwise all reagents were ultrapure. All complementreagents are from Complementech, Tylar Tex. or from Quidel Corporation,San Diego, Calif. GVB for classical pathway, Phosphate buffered salinewas purchased from Sigma-Aldrich, St Louise Mo., GVB for alternativecomplement pathway was purchased from Complemmentech, Tylar, Tex., Allflow cytometry antibodies were from BD Biosciences, San Jose, Calif.,TMB substrate was from Kirkegaard & Perry Limited, Gaithersberg, Md.,rRBC and sheep erythrocytes (antibody sensitized) were fromComplementech, Tylar, Tex., All secondary antibodies were from AmericanQualex, San Clemente, Calif., BSA and other reagents were all fromSigma-Aldrich, St Louise, Mo. Normal Human serum was freshly isolatedusing BD Biosciences Clotting tubes.

ELISA plate readers (SpectraMax 190 and 250) were from MolecularDevices, and Flow Cytometer was FACSCalibur. Varity 3D program was usedfor data analyses, Curve fittings were done using MicroCal Originprogram. Hemolysis kinetic assay was run using SectraMax, MolecularDevices, ELISA plates were from Corning Costar, Lowell, Mass.

It would be evident to the one skilled in the art that in vitro studiesof complement are representative of and predictive of the in vivo stateof the complement system. By way of example, the use of in vitro ELISA(Enzyme Linked Immunosorbent Assay) procedures to detect factor Bbassociated with lipopolysaccharide (LPS) is a “simple, rapid andreliable method for the assessment of complement function particularlythe detection of complement deficiency states”. Thus, the in vitrotechnique can be used in vivo with the same likelihood of success indetecting alternative complement pathway activation in disease states.Furthermore, the standard rabbit erythrocyte hemolysis assay, whichassay is used to measure alternative complement pathway activity, isaccepted in the art as being the “most convenient assay for the activityof the human alternative pathway”.

Example 1 Assembly of C3 Convertase: Interactions of Factor B, C3b andProperdin

It is known that Factor B binds C3b. It is also known that properdinbinds C3b and that C3 convertase (PC3bBb) is stabilized in the presenceof properdin. It has been debated whether properdin binds first or itbinds after the C3bBb convertase is already formed. It is known that ifAP activation does not proceed, C3b begins to degrade by the action offactors H and I into iC3b, C3c, and C3dg. The conversion of C3b intosmaller fragments is indicative of degradation route of C3b. It isassumed that in a given system at a given time, there would be somedegraded C3b components could exist. We evaluated whether B would bindC3b and PC3b with different affinities. We also evaluated iC3b, C3c, andC3dg for factor B binding in the presence and absence of properdin.

Factor B Binding to C3b and PC3b using ELISA Based Binding Assays

In the first experiment (FIG. 6), wells were coated with C3b (1 μg/50 μlper well) overnight. The plates were blocked with 1% BSA in PBS. Afteraspirating the protein solution, the wells were washed and incubatedwith factor B in the presence or absence of properdin (5 nM final).Following a 2 h incubation at room temperature, the wells were washedand incubated with the anti-properdin #2 antibody from Quidelcorporation at 1:2000 dilution in blocking solution. Following a 1 hincubation, the plate was rinsed with PBS and incubated with HRPOconjugated goat anti-mouse monoclonal antibody at 1:2000 dilution inblocking solution. Again, after a 1 h incubation, the wells were rinsedwith PBS and the color was developed with TMB substrate using standardprocedure. As shown in FIG. 6, the affinity of B binding to C3b ishigher in cases when properdin is attached to C3b. We wanted todetermine if properdin would bind the factor B. As shown in FIG. 6,Factor B binds with high affinity to properdin bound C3b.

Factor B Binding to Properdin

ELISA wells were coated with Factor B (2 μg/50 μl/well). The plate wasincubated in cold overnight. The plate was blocked with 1% BSA in PBSfor 2 hours at room temperature. ELISA wells were incubated withproperdin in various concentrations. The plate was incubated for 2hours, following which properdin was detected as above. As shown,properdin does not bind factor B (FIG. 7)

Factor B Binding to Isoforms of C3b which are iC3b, C3c, C3dg

Polystyrene microtiter plates were coated with human iC3b, C3c, or C3dg(1.0 μg/50 μl per well) in phosphate buffered saline (PBS) overnight at4° C. Following blocking and washing using standard methods, aliquots offactor B at varying concentration in AP buffer were added and plateswere allowed to incubate for 2 hours. Factor B binding to various C3isoforms was measured by adding detection antibody (Quidel, San Diego,Calif., anti-human factor B antibody) at 1:2000 dilution in blockingsolution. The plate was allowed to incubate for 1 hour at roomtemperature. After washing the plates with PBS, a peroxidase-conjugatedgoat anti-mouse antibody (1:2000 dilution in blocking solution) wasadded and allowed to incubate for 1 hour. The plate was again rinsedthoroughly with PBS, and 100 μl of 3,3′,5,5′-tetramethyl benzidine (TMB)substrate was added. After incubation for 30 minutes at 25C., thereaction of TMB was quenched by the addition of 100 μl of phosphoricacid, and the plate was read at 450 nm in a microplate reader. In aseparate experiment to evaluate the effect of the presence of properdin,an aliquot of properdin 5 nM was incubated for 1 hour in blockingsolution on C3b isoforms coated plates. Following washing with PBS fivetimes, various concentrations of factor B were added as above and therest of the assay was performed as described above. FIG. 8 demonstratesthat factor B does not bind any isoform of C3b except the protein C3b.

Example 2 Screening and Selection of Anti-Factor Bb MonoclonalAntibodies

Six mice were injected with Factor B antigen. Mice sera were removed andevaluated for factor B binding as shown in FIG. 9. All sera containingthe mouse serum were diluted and incubated with factor B coated plates.The binding of anti-factor B monoclonal was determined withPeroxidase-conjugated goat anti-mouse IgG. The data was plotted usingMicroCal Origin program. In a typical assay, polystyrene microtiterplates were coated with human factor B (2 μg/50 μl per well, (ComplementTechnologies, San Diego, Calif.) in phosphate buffered saline (PBS)overnight. After aspirating the factor B solution, wells were blockedwith PBS containing 1% bovine serum albumin (BSA) (Sigma ChemicalCompany, St. Louis, Mo., Cat. No. A7888) for 2 hours at roomtemperature. Wells without factor B coating served as backgroundcontrols. Aliquots of diluted hybridoma supernatants in blockingsolutions at various dilutions were added to factor B-coated wells andplates were allowed to sit for 1 hour to allow the monoclonal antibodyto bind the substrate-bound factor B. The plate was rinsed with PBS andfactor B-bound monoclonal was detected by the addition of mousemonoclonal anti-human factor B antibody (detection antibody) (Quidel,San Diego, Calif., anti-human factor B monoclonal) at 1:2000 dilution inblocking solution, which was allowed to incubate for 1 hour at roomtemperature. After washing the plates with PBS, a peroxidase-conjugatedgoat anti-mouse antibody (1:1000 dilution in blocking solution) (SigmaChemical Company) was added and allowed to incubate for 1 hour. Theplate was again rinsed thoroughly with PBS, and 100 μl of3,3′,5,5′-tetramethyl benzidine (TMB) substrate (Kirkegaard & PerryLaboratories, Gaithersburg, Md., Cat. No. A50-65-00) was added. Afterincubation for 10 minutes at 25° C., the reaction of TMB was quenched bythe addition of 100 μl of phosphoric acid, and the plate was read at 450nm in a microplate reader (e.g., SPECTRA MAX 250, Molecular Devices,Sunnyvale, Calif.). Sera from all six mice bound factor B with lowdilutions of serum. As shown in FIG. 9, all mice demonstrated comparabletiter.

Sera from all six mice were also subjected to the alternative pathwaydependent hemolysis assay. In this assay, fixed number of rabbiterythrocytes were incubated with 10% normal human serum in Buffer thatallows only alternative pathway to be activated. The cellular mixturewas incubated with various with mice sera and incubated at 37 C. Aprogressive decrease in light scatter (due to lysis of intact cells) wasmeasured at 700 nm as a function of time in a temperature-controlledELISA plate reader. The data were recorded and analyzed with aSpectraMax plate reader and SoftMax pro software. As shown in FIG. 10,Mouse A3 demonstrated near complete inhibition with the 1;10 dilutedsera. The same mouse demonstrated a good titer in FIG. 9. These two datasets combined together suggest the selection of mouse A3 for furthercloning and hybridoma production.

The spleen from the selected mouse was removed and fused with themyeloma cells to generate hybridoma. To generate clonal line, thehybridoma cells were distributed in 9 plates with 60 wells in each toallow each well to contain one cell each. These cells were allowed togrow in under appropriate culture conditions. The media was collectedand evaluated for factor B binding using factor B coated plates. Asshown in FIG. 11, only few clones demonstrated factor B binding.

Factor B positive clones were then evaluated in a C3b generation assay.In this assay, microtiter wells were coated with LPS (2 μg/50 μl perwell) in PBS overnight at 4° C. Uncoated wells served as backgroundcontrols. After aspirating the LPS solution, wells were treated withblocking solution and incubated with a fixed concentration of normalhuman serum with and without hybridoma supernatant in AP buffer (GelatinVeronal Buffer with 5 mM MgC12, Complement Technologies). Following a2-h incubation at 37° C., deposited C3b was detected with mouseanti-human C3b antibody (Quidel Corporation) using standard ELISAmethodologies essentially as described in the Examples above. The effectof the blocking antibody on the C3b formation is shown in FIG. 12. Asshown, only a single clone named 1D3 inhibits C3b production. Thisparticular clone 1D3 was further evaluated in rRBC hemolysis assay andwas found to inhibit hemolysis of rRBC in AP buffer as shown in FIG. 13.

Example 3 Production and Purification of 1D3

1D3 secreting clone was isolated and expanded in culture. To producelarge amounts of purified monoclonal antibody, 1D3 cells were injectedinto mice to produce tumors. The ascites fluid from such tumors weretested for blocking monoclonal antibody activity. As shown in FIG. 14,the monoclonal antibody (NM001) present in ascites fluid blockshemolysis of rRBC in normal human serum. The blocking monoclonalantibody was purified using protein-G column (purity shown in FIG. 15)and again tested for blocking activity using rRBC as described inExample 1. As shown in FIG. 16, NM001 prevents hemolysis of rRBC at aconcentration of 100 ug/ml. NM001 was fragmented into F(ab)2 using Ficinas per previously published methods. The purified fragment was named asBikaciomab.

Example 4 Binding Affinity of NM001 and Bikaciomab to Factors B

NM001 binds factor Bb with high affinity. NM001 did not bind the Bafragment. As shown in FIG. 17, the binding of NM001 to factor B issaturable. FIG. 17 shows high affinity binding of NM001 to Bb fragment.In a typical assay, polystyrene microtiter plates were coated with humanfactor Bb (2 μg/50 μl per well, (Complement Technologies, San Diego,Calif.) in phosphate buffered saline (PBS) overnight. After aspiratingthe factor Bb solution, wells were blocked with PBS containing 1% bovineserum albumin (BSA) (Sigma Chemical Company, St. Louis, Mo., Cat. No.A7888) for 2 hours at room temperature. Wells without factor Bb coatingserved as background controls. Aliquots of various concentrations ofNM001 in blocking solutions were added to factor Bb-coated wells andplates were allowed to sit for 1 hour to allow the monoclonal antibody(NM001) to bind the substrate-bound factor Bb. The plate was rinsed withPBS and factor Bb-bound monoclonal antibody (NM001) was detected by theaddition of peroxidase-conjugated goat anti-mouse monoclonal antibody(detection antibody) (Sigma-aldrich, San Diego, Calif.) at 1:2000dilution in blocking solution, which was allowed to incubate for 1 hourat room temperature. After washing the plates with PBS, 100 μl of3,3′,5,5′-tetramethyl benzidine (TMB) substrate (Kirkegaard & PerryLaboratories, Gaithersburg, Md., Cat. No. A50-65-00) was added. Afterincubation for 10 minutes at 25° C., the reaction of TMB was quenched bythe addition of 100 μl of phosphoric acid, and the plate was read at 450nm in a microplate reader (e.g., SPECTRA MAX 250, Molecular Devices,Sunnyvale, Calif.).

In a separate experiment, we evaluated the binding of Bikaciomab tofactor Bb. As shown in FIG. 24, Bikaciomab binds factor Bb with highaffinity. Basic methodology for these assays is described in theparagraph above.

Example 5 Evaluation of NM001 and BikacioMab in Alternative PathwayRabbit Erythrocyte Lysis

This cellular assay is based on the formation of terminal complementcomplex on the surface of the rRBC. As a result, the rRBC are lysed. Theevidence of lysed cells is reflected in progressive decrease in lightscatter at 700 nm. rRBC are incubated in normal human serum in APbuffer. The surface of rRBC triggers the activation of AP in normalhuman serum. AP cascade begins and leads to the formation of C5b-9complex on the surface of the rRBC. Agents that inhibit the activationare expected to inhibit cellular lysis.

To evaluate the effect of NM001 on AP activation, various concentrationsof NM001 in AP buffer were incubated with normal human serum (10% NHS)at 37° C. with a fixed number of rabbit erythrocytes (Covance) in atemperature controlled ELISA plate reader capable of reading at 700 nm.A progressive decrease in light scatter (due to lysis of intact cells)was measured at 700 nm as a function of time. The data were recorded andanalyzed with a SpectraMax 190 plate reader and SoftMax Pro software.Total inhibition was calculated at each concentration of the NM001 andthe results were expressed as a % of unlysed controls. Data at eachconcentration was plotted in a sigmoidal plot with MicroCal OriginSoftware. FIG. 18 shows that NM001 inhibits AP activation in thiscellular assay.

FIG. 25 demonstrates the potent activity of BikacioMab in inhibitingerythrocyte lysis. The antibody was able to inhibit lysis in a dosedependent manner. The graph shows that the BikacioMab inhibits lysis ina dose dependent manner.

Example 6 NM001 Does Not Inhibit Factor B Binding to C3b

It has been previously shown that inhibition of factor B binding to C3bis required for inhibition of complement activation. Therefore,antibodies that do not inhibit C3b-B binding are not expected to inhibitAP activation.

Surprisingly, our results demonstrate that NM001 does not inhibit factorB binding to C3b in the presence and absence of properdin. In a typicalassay to evaluate the effect of NM001 on factor B binding to C3b,polystyrene microtiter plates were coated with human C3b (0.5 μg/50 μlper well) (Calbiochem, San Diego, Calif., Cat. No. 204860) in phosphatebuffered saline (PBS) overnight at 4 degree. After aspirating the C3bsolution, wells were blocked with PBS containing 1% BSA (Sigma ChemicalCompany, St. Louis, Mo., Cat. No. A7888) for 2 hours at roomtemperature. Wells without C3b coating served as background controls.Aliquots of human factor B (Complement Technologies, Tyler, Tex.) at afixed concentration (100 nM) in blocking solution (containing 5 mMMgC12) were added to the wells in the presence and absence of variableconcentration of NM001. Following 2 hour incubation at room temperature,the wells were extensively rinsed with PBS and C3b-bound factor B wasdetected by the addition of goat anti-human factor B polyclonal antibodyat 1:5000 dilution in blocking solution, which was allowed to incubatefor 1 hour at room temperature. After washing the plates with PBS, aperoxidase-conjugated rabbit anti-goat antibody (1:5000 dilution inblocking solution) (American Qualex) was added and allowed to incubatefor 1 hour. The plate was again rinsed thoroughly with PBS, and 100 ulof 3,3′,5,5′-tetramethyl benzidine (TMB) substrate (Kirkegaard & PerryLaboratories, Gaithersburg, Md., Cat. No. A50-65-00) was added. Afterincubation for 10 minutes at 25° C., the reaction of TMB was quenched bythe addition of 100 μl of phosphoric acid, and the plate was read at 450nm in a microplate reader (e.g., SPECTRA MAX 250, Molecular Devices,Sunnyvale, Calif.).

As shown in FIG. 19, NM001 inhibits factor B binding to C3b in thepresence and absence of properdin (40 nM). These results were surprisingin light of previously known concept where inhibition of factor Bbinding to C3b was required for complete blockade of complementactivation. To confirm these findings factor B solution was replacedwith 10% normal human serum and the rest of the experiment was conductedas described in the paragraph above. As shown in FIG. 20, NM001 does notinhibit Factor B binding to C3b. The results shown in FIG. 19 parallelthe results shown in FIG. 20 demonstrating that NM001 does not preventfactor B binding to C3b.

Example 7 NM001 and BikacioMab Inhibit C3b Formation

The binding data above reveal that NM001 and BikacioMab do not preventthe binding of factor B to C3b. Since factor B is the critical componentof the C3 convertase, it was of interest to us to determine whether thelack of factor B binding to C3b might appreciably affect the formationof additional C3b molecules for the amplification of the AP activation.To analyze the effects of the factor B antibody on C3b formation via thealternative pathway, an assay was utilized in which bacterial LPS wasused as a substrate to initiate the alternative complement pathwaycascade. Previous studies have demonstrated that lipopolysaccharide(LPS) from Salmonella typhosa (S. Typhosa) (Sigma Chemical Company, Cat.No. 6386) serves as a potent substrate for complement alternativepathway activation. Microtiter wells were coated with LPS (2 μg/50 μlper well) in PBS overnight at 4° C. Uncoated wells served as backgroundcontrols. After aspirating the LPS solution, wells were treated withblocking solution and incubated with 10% concentrations of normal humanserum containing various concentrations of NM001 (FIG. 21) or Bikaciomab(FIG. 27). Following a 2 hour incubation at 37° C., deposited C3b wasdetected with mouse anti-human soluble C3c monoclonal antibody (Quidel,San Diego, Calif.) using standard ELISA methodologies essentially asdescribed in the Examples above. Both FIGS. 21 and 27 demonstrate thatthe monoclonal antibody NM001 is capable of inhibiting the C3b formationwithout inhibiting the formation of C3b binding to factor B.

In a separate assay, we detected properdin using Quidel anti-P#2antibody and showed that NM001 inhibits properdin deposition. While theantibody does not interfere with the binding of Properdin to C3b, theNM001 prevented C3b deposition that was pre-bound to C3b (FIG. 23).

Example 8 NM001 and Bikaciomab Inhibit C5b-9 Formation

The binding data above reveal that the factor B monoclonal antibody doesnot prevent the binding of factor B to C3b. Since factor B is thecritical component of the C3 convertase, it was of interest to us todetermine whether the lack of factor B binding was required for C5b-9formation because this monoclonal was originally identified usinginhibition of C5b-9 in a cellular assay. To analyze the effects of thefactor B antibody on C5b-9 formation via the alternative pathway, anassay was utilized in which bacterial LPS was used as a substrate toinitiate the alternative complement pathway cascade. Previous studieshave demonstrated that lipopolysaccharide (LPS) from Salmonella typhosa(S. Typhosa) (Sigma Chemical Company, Cat. No. 6386) serves as a potentsubstrate for complement alternative pathway activation. Microtiterwells were coated with LPS (2 μg/50 μl per well) in PBS overnight at 4degree. Uncoated wells served as background controls. After aspiratingthe LPS solution, wells were treated with blocking solution andincubated with 10% concentrations of normal human serum containingvarious concentrations of NM001 (FIG. 22) or Bikaciomab (FIG. 28).Following a 2 hour incubation at 37° C., deposited C5b-9 was detectedwith mouse anti-human C5b-9 monoclonal antibody (Quidel, San Diego,Calif.) using standard ELISA methodologies essentially as described inthe examples above. Both FIGS. 22 and 28 demonstrate that the anti-Bb iscapable of inhibiting the C5b-9 formation without inhibiting theformation of C3b binding to factor B.

Example 9 BikacioMab Does Not Inhibit the Classical Pathway Activation

The Monoclonal antibody Bb of the present invention does not inhibit theclassical pathway. The classical pathway is important for host defense.In this assay, Antibody sensitized sheep erythrocytes is incubated withNormal Human Serum in buffer appropriate for CP activation. Theantigen-Antibody complex on the surface of the sheep cells activates theclassical complement pathway. As a result erythrocyte lysis occurs.Classical pathway activation occurs in low concentration of serum (1%final). While the knockout mouse data suggests that factor B mayparticipate in classical pathway activation, but our results demonstrateno involvement of the classical pathway.

In a typical assay, erythrocytes are incubated in 1% normal human serumin CP buffer to allow complement activation to occur. As a result of CPactivation, C5b-9 is formed on the surface of erythrocytes causingcellular lysis. The progressive decrease in light scattering is measuredat 700 nm as a function of time.

As shown in FIG. 26, Bikaciomab does not inhibit the classicalcomplement pathway activation. These surprising results further suggestthat antibodies can be made that inhibit the specifically prevent the APactivation without affecting the classical pathway. Development ofmonoclonal antibodies of this invention will leave the classical pathwayintact for host defense against infection.

Example 10 Efficacy of BikacioMab in a Tubing Loop Model ofCardiopulmonary Bypass

Examples 1 through 9 demonstrate the evaluation of BikacioMab in invitro in the presence of human serum. In any disease condition,neutrophils, monocytes and platelets orchestrate the inflammatoryresponse and are critical cell types for clinical control. We have notyet showed the data on the cellular activation. We have chosen thissimple model of cardiopulmonary bypass to demonstrate that BikacioMabcan prevent cellular activation. In order for the anti-Bb to be a viabledrug we need to determine if BikacioMab would inhibit the activation ofneutrophils, monocytes, and platelets.

It is known that as blood comes in contact with the artificial surfacesof the extracorporeal circuit, there is significant activation of thealternative complement pathway. To test the effect of Bikaciomab(anti-Bb), Whole blood from a healthy donor was collected into apolypropylene tube containing 5 units of heparin per ml of whole blood.The whole blood was diluted 1:1 with plasmalyte and was aliquoted in 2ml aliquots with and without drug treatments. PVC tubings were filledwith 2.0 ml of the heparinized human blood and closed into a loop with ashort piece of silicon tubing. Sample and control tubing loops wererotated vertically in a water bath for 2 hours at 37° C. Afterincubation, blood samples were transferred into 5 ml siliconizedeppendorf tubes. The samples were separated into two aliquots; onealiquot was subjected to flow cytometry studies for cellular activationand the other aliquot was centrifuged to separate the plasma forserological markers. To evaluate the effect of BikacioMab on complementand cellular activation, various concentrations of Bikaciomab were mixedwith blood prior to the tubing loop rotation. All tubing loops wererotated at 37° C. for 2 hours before cellular and complement activationis measured.

The plasma samples were diluted to 5% with sample diluent buffer andevaluated in a C3a, C5a and sC5b-9 using ELISA assay kits following themanufacturer's instructions (Quidel, Catalog Nos. A015 for C3a and A009for C5b-9). As shown in FIG. 29, BikacioMab inhibits C3a production inwhole blood in a dose dependent manner with complete inhibitionoccurring at 100 ug/ml of BikacioMab. The IC50 of inhibition is in therange of 20 μg/ml. Similar results were obtained with C5a measurements.BikacioMab completely inhibits C5a (FIG. 30) formation and C5b-9 (FIG.31) formation in a dose dependent manner.

Aliquots of blood following the tubing loop were stained withfluorescent labeled antibodies for flow cytomtery studies. Neutrophilswere labeled with FITC labeled CD15 and PE labeled CD11b antibodies,monocytes were stained with FITC labeled CD14 and PE labeled CD11bantibodies, and platelets were stained with FITC labeled CD61 and PElabeled CD62P. In a typical method; 20 μl of each of the labeledantibodies were added to the 100 μl of staining buffer containing 50 μlof whole blood. The staining was continued for 20 minutes, followingwhich 2.0 ml of the staining solution was added and the red blood cellswere allowed to lyse for 20 minutes. The solution was centrifuged andthe cell pellet was washed with PBS and suspended in 0.5 ml ofpara-formaldehyde solution. The samples were subjected to flow cytometryusing CellQuest, BD-LSR I and the data were analyzed using WinList 5.0.Ln Median was used for calculating the shift in CD11b staining forneutrophils and monocytes. % gated dual labeled cells were quantifiedfor platelet populations. FIGS. 32, 33, and 34 show that BikacioMabinhibits neutrophil, monocyte, and platelet activation. Completeinhibition with BikacioMab suggests that the anti-Bb antibody is capableof complete inhibition of cellular activation and that cellularactivation is complement dependent.

To further demonstrate that Bikaciomab inhibits neutrophil elastaserelease by neutrophils, aliquots of plasma were also evaluated forneutrophil elastase ELISA developed in-house. In a typical ELISA,anti-elastase antibody was used at 1:500 dilution as a coating antibody.Aliquots of plasma were added to antibody coated wells. The boundelastase-anti-trypsin complex was detected with HRP-conjugatedanti-trypsin monoclonal antibody diluted at 1:500 dilution. As shown inFIG. 36 Bikaciomab inhibits elastase release by neutrophils in wholeblood. TNF alpha was also measured using BD Kit. The data shown in FIG.35 shows that Bikaciomab inhibits TNF alpha production. Given the roleof TNF in arthritis, the drug anti-Bb can be used in treating severaldisease indications.

Results

BikacioMab is an F(ab)2 fragment of an anti-Bb monoclonal antibody. Themonoclonal antibody is a potent inhibitor of protease activity whichbinds in the Bb region of factor B. Bikaciomab binds the Bb region withhigh affinity and inhibits C3a, C5a, and C5b-9 formation. Inhibition ofneutrophil, monocyte and platelet activation mirrors the inhibition ofcomplement. Activation of platelet is complement dependent. Bikaciomabtotally prevents cellular activation. BikacioMab is characterized as ananti-inflammatory and anti-platelet drug which may be superior toReoPro. BikacioMab would be an ideal drug for all those clinicalindications where alternative complement pathway plays a role in diseasepathology.

1.-69. (canceled)
 70. An isolated antibody or antigen binding portionthereof, comprising: the heavy chain variable regions and the lightchain variable regions of an antibody produced by the hybridoma cellline deposited under ATCC Accession Number PTA-8543.
 71. The antibody ofclaim 70, wherein the antibody is monoclonal.
 72. The antibody of claim71, wherein the antibody is chimeric, recombinant, humanized,de-immunized, or fully human antibody.
 73. The antibody of claim 70,wherein the antibody is a single chain antibody, IgG, F(ab)2, F(ab′)2,F(ab), F(ab′) fragment, or truncated antibody.
 74. The antibody of claim70, wherein the ratio of antibody binding to factor B is about 0.5:1 toabout 2:1.
 75. A method of inhibiting alternative complement pathwayactivation in a mammal, the method comprising: administering to themammal an amount of an antibody and/or fragment thereof thatspecifically binds to an epitope of Bb segment of the factor B effectiveto inhibit alternative complement pathway in the mammal.
 76. The methodof claim 75, wherein the antibody is monoclonal.
 77. The method of claim76, wherein the antibody is chimeric, recombinant, humanized,de-immunized, fully human, or truncated antibody.
 78. The antibody ofclaim 75, wherein the antibody is a F(ab), F(ab′), F(ab)2, F(ab′) 2, Fv,single chain fragment, truncated F(ab)2, IgG, or truncated IgG.
 79. Themethod of claim 75, wherein the ratio of antibody or fragment thereofbinding to factor B is about 0.5:1 to about 2:1.
 80. The method of claim75, wherein as a result of administering the antibody and/or fragmentthereof to the mammal at least one of factor B binding to C3b is notinhibited, the formation of C3bB is reduced, C3bBb formation is reduced,C3a and C5a production is reduced, C5b-9 complex formation is reduced,activation of neutrophils is reduced, activation of monocytes isreduced, activation of platelets is reduced, formation ofleukocyte-platelet conjugates is reduced, or Ba production is reduced.81. The method of claim 75, wherein the antibody or fragment thereofinhibits alternative pathway dependent rabbit erythrocyte lysis in humanserum/plasma.
 82. The method of claim 75, wherein the antibody orfragment thereof is administered in vivo or ex vivo.
 83. The method ofclaim 75, wherein the antibody or fragment thereof specifically binds toan epitope within the serine protease domain or VWA domain of factor Bor Bb.
 84. The method of claim 83, wherein the antibody and/or fragmentthereof specifically binds to the catalytic triad Asp-His-Ser in theserine protease domain of factor B and its Bb fragment.
 85. The methodof claim 75, wherein the antibody or fragment thereof specifically bindsto Bb and inhibits C3b oligomer formation by way of preventing formationof additional C3b molecules which otherwise would associate withexisting C3b to form oligomers.
 86. The method of claim 75, wherein theantibody or fragment thereof prevents production of additional C3bmonomers.
 87. The method of claim 75, wherein the antibody or fragmentthereof blocks the alternative pathway activation without affecting theclassical pathway activation.
 88. The method of claim 75 wherein theantibody or fragment thereof does not prevent Factor B or Bb binding toC3b/PC3b.
 89. The method of claim 75 wherein the antibody or fragmentthereof increases the clearance of the complex C3bBb-antifactor Bb agentvia the CRI receptors on erythrocytes.
 90. The method of claim 75,wherein the antibody or fragment thereof comprises the heavy chainvariable regions and the light chain variable regions of an antibodyproduced by the hybridoma cell line deposited under ATCC AccessionNumber PTA-8543.
 91. A method of treating alternative pathway activationmediated by disease-related or pathological conditions, the methodcomprising: administering to a mammal a therapeutically effective amountof an antibody or fragment thereof that specifically binds to an epitopeof Bb that blocks the alternative pathway activation without affectingthe classical pathway activation.
 92. The method of claim 91, whereinthe antibody is a monoclonal antibody.
 93. The method of claim 91,wherein the antibody is a chimeric, recombinant, humanized, de-immunizedor fully human antibody.
 94. The method of claim 91, wherein the diseaseor condition is selected from the group consisting of atherosclerosis,ischemia-reperfusion following acute myocardial infarction,Henoch-Schonlein purpura nephritis, immune complex vasculitis,rheumatoid arthritis, arteritis, aneurysm, stroke, cardiomyopathy,hemorrhagic shock, crush injury, multiple organ failure, hypovolemicshock and intestinal ischemia, transplant rejection, cardiac Surgery,PTCA, spontaneous abortion, neuronal injury, spinal cord injury,myasthenia gravis, Huntington's disease, amyotrophic lateral sclerosis,multiple sclerosis, Guillain Barre syndrome, Parkinson's disease,Alzheimer's disease, acute respiratory distress syndrome, asthma,chronic obstructive pulmonary disease, transfusion-related acute lunginjury, acute lung injury, Goodpasture's disease, myocardial infarction,post-cardiopulmonary bypass inflammation, cardiopulmonary bypass, septicshock, transplant rejection, xeno transplantation, burn injury, systemiclupus erythematosus, membranous nephritis, Berger's disease, psoriasis,pemphigoid, dermatomyositis, anti-phospholipid syndrome, inflammatorybowel disease, hemodialysis, leukopheresis, plasmapheresis,heparin-induced extracorporeal membrane oxygenation LDL precipitation,extracorporeal membrane oxygenation, macular degeneration, andcombinations thereof.
 95. The method of claim 91, wherein the antibodyor fragment thereof comprises the heavy chain variable regions and thelight chain variable regions of an antibody produced by the hybridomacell line deposited under ATCC Accession Number PTA-8543.